Hydrogen production by catalytic steam-hydrocarbon reforming is typically performed in catalyst-containing reformer tubes in a reforming furnace. The catalyst-containing reformer tubes are cycled from ambient temperature to high operating temperatures during startup and then back to ambient temperature during a shutdown, which can be planned or unplanned.
Catalyst pellets are packed in the reformer tubes. When the reformer tubes are heated, the diameters of the reformer tubes increase due to thermal expansion and while the catalyst pellets may also expand due to thermal expansion, there is an expansion mismatch and the catalyst pellets resettle in the tubes, filling up the space created by the tube expansion. When the reformer tubes are later cooled during a shutdown, the diameters of the reformer tubes decrease. The catalyst pellets, which are tightly packed in the reformer tubes, are compressed by the reformer tube walls and the catalyst pellets may break.
The pieces of the broken catalyst pellets may fill in the interstitial space between the catalyst pellets and thereby cause increased flow resistance for the reactant gases flowing through the reformer tubes. The increased flow resistance increases the pressure drop in the reformer tubes. The densification of the catalyst bed may occur locally leading to maldistribution of the reactant gases flowing through the packed bed which can lead to hot spot formation on the reformer tube walls.
Reformer tube failures are typically associated with high metal temperatures, but may also be associated with catalyst compaction.
Industry desires to be able to thermally cycle reformer tubes in order to accommodate startup and shutdown of the reformer furnace.
Industry desires to avoid and prevent crushing and breaking of catalyst pellets in the reformer tubes.
Industry desires the ability to extend the life of the reformer catalyst and not to have to replace the catalyst due to “hot spots” or flow maldistribution that results from catalyst compaction.
Industry desires to avoid and prevent rupture of reformer tubes.
Industry desires solutions to the above problems that do not decrease the efficiency and/or capacity of the steam-hydrocarbon reforming process.